In this work, three different thermal protocols were tested on untreated and
water-washed aerosol samples to study the influence of soluble organic and
inorganic compounds on EC measurements. Moreover, analyses on the water
soluble extracts were carried out. The aim was to find out the most suitable
protocol to analyse samples collected in a heavily polluted area. Indeed,
the tests were performed on real samples collected at an urban background
station in the Po Valley, which is one of the main pollution hot-spots in
Europe.
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The main differences among the tested protocols were the maximum temperature
of the He step (i.e. 870 °C, 650 °C, and 580 °C) and the duration
of the plateaus during the heating procedure. Our measurements evidenced the
presence of a significant amount of weakly light-absorbing carbonaceous aerosol evolving
during the highest temperature step in He (i.e. 870 °C), which makes
lower temperature protocols not suitable for EC determination in samples
collected in heavily polluted areas like Milan.